Glaucoma: the tests that make it possible to diagnose it!
And if you take advantage of World Sight Day on October 9 to make an appointment with an ophthalmologist and check that you do not have glaucoma? One person in two would be affected but not diagnosed.
Glaucoma: the tests that make it possible to diagnose it
Summary
Glaucoma: risk factors
Glaucoma: the importance of screening
Glaucoma: screening how is it going?
Glaucoma: risk factors
Glaucoma is an optic nerve disease that destroys more or less rapidly charged cells of the retina transmitting the images captured by the eye to the brain. A formidable disease, it evolves silently, without pain and you have neither symptoms nor loss of vision. It is estimated that one in two people with glaucoma remains ignorant until it is too late: when the visual field begins to decrease, lost vision can not be regained.
The main risk factors are:
- Strong myopia (which multiplies the risk by 3?
- increased intraocular pressure (the aqueous humor accumulates behind the iris and increases the pressure inside the eye)
- high blood pressure
- sleep apnea
- genetic predispositions (the same as for coronary insufficiency or an intracranial aneurysm).
- the use of pesticides.
Glaucoma: the importance of screening
In France, about 800,000 people are treated for primary open-angle glaucoma, also known as chronic glaucoma. But the French Society of Ophthalmology estimates that the same number of people would be affected but undiagnosed: "A recent epidemiological meta-analysis reports that glaucoma affects 2.6% of the population. Is undiagnosed and goes unknowingly to absolute blindness, "explains Professor Christophe Baudouin, head of the XV-XX department in Paris.
Open-angle glaucoma, which is the most frequent form of the disease in France, evolves for a long time without any apparent symptoms: no pain, no redness of the eye, central vision remains clear. And when the first disturbances of vision are observed, the optic nerve is already largely destroyed. "Only examinations, simple and painless, carried out by an ophthalmologist make it possible to detect and treat it" insists Professor Baudouin.
Glaucoma: screening how is it going?
"The measurement of the intraocular pressure and the examination of the origin of the optic nerve in the fundus of the eye make it possible to diagnose the disease in a first step, then the evaluation of the visual field and a gonioscopy (that is, An examination of the angle between the iris and the cornea) will make it possible to specify the nature of glaucoma and its stage of advancement "explains the ophthalmologist.
Measurement of the intraocular pressure is done by means of a tonometer. More and more ophthalmologists opt for the contactless version by sending a jet of air into the eye, which no longer requires the use of anesthetic eye drops. Another method consists in exerting a sufficient pressure on the cornea to flatten it by means of a plastic cone. But this examination requires the administration of an anesthetic eye drops.
The examination of the optic nerve is performed by an ophthalmoscope, an apparatus which emits light which illuminates the inside of the eye and thus makes visible the starting point of the nerve. This allows the ophthalmologist to find that there are lesions or not. This examination lasts only a few minutes but may require dilating the pupils with eye drops.
Measurement of the visual field (also called perimetry) consists of fixing a central point in a dome, while small luminous tests appear briefly in the different parts of the visual field. It is necessary to indicate as and when the lights are perceived, which makes it possible to realize if there are zones missing.
Gonioscopy (or examination of the iridocorneal angle) consists of observing the opening of the angle between the iris and the cornea (the transparent part of the eye) by means of a special magnifier placed on the surface Of the eye. This examination is performed under local anesthesia by the instillation of drops into the eye. This examination is necessary to distinguish the type of glaucoma and to be able to choose the appropriate treatment.
"These last two examinations are not carried out systematically by the ophthalmologist but," Ã la carte "according to the medical situation of the patient, mainly when the eye pressure is high or the observation of the fundus eye suspects an Impairment of the optic nerve. Their interpretation can only be done by an ophthalmologist experienced in this field, "concludes Professor Baudouin.
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Researchers at Northwestern University in Illinois, United States, have discovered the mechanism behind this degenerative disease of the optic nerve, which can lead to blindness.
Glaucoma is a disease associated with too high intraocular pressure which eventually damages the optic nerve fibers and the retina, resulting in progressive loss of vision. This pathology is due to blockage of the passage of cells in the Schlemm canal. This canal allows the drainage of the aqueous humor, a liquid that protects the lens and nourishes the cornea.
Researchers at Northwestern University believe they have discovered the origin of this problem of "plumbing" associated with high pressure and the onset of Glaucoma. In the scientific journal Proceedings of the National Academy of Sciences (PNAS), they refer to the real culprit: it is a mechanical dysfunction of the endothelial cells located at the entrance of the Schlemm canal. This failure would disrupt the normal circulation of the "eye fluid". In the case of glaucoma, these cells become stiffer than normal cells. This rigidity would prevent the cells from deforming and allowing the aqueous humor to pass normally through the Schlemm canal. It is, therefore, this resistance of the flux that would explain the occurrence of glaucoma according to the researchers.
While there is no treatment to treat glaucoma, this discovery could be a pathway to fight this disease. "Our study shows that endothelial cells act as automatic doors, and therapeutic strategies capable of modifying these cells could potentially lead to treatment of this eye condition," the study concludes.
Glaucoma: an implant to prevent blindness
Are eye implants the new alternative to surgery? After the "raindrop" implant intended to permanently correct presbyopia, the researchers announce the arrival of an ocular implant that would allow following the evolution of glaucoma and, therefore, to prevent blindness.
Glaucoma is an eye disease that affects about 1 million people in France. The liquid from the inside of the eye, the aqueous humor, is evil or more evacuated at all. It accumulates, which increases the pressure inside, eventually degrading the retina and the optic nerve. Without treatment, the vision gradually decreases and one can become blind.
What makes glaucoma dangerous is that the disease evolves silently. People who are affected do not realize that they are losing part of the vision because the brain is doing an incredible job to compensate for this loss of vision. And when loss of vision becomes important, it is irreversible.
A sensor implanted in a lens
For now, the only way to determine the severity of Glaucoma in patients is to measure intraocular pressure in an area of the cornea (the transparent part of the eye). But, even in the hands of experts, the measuring device is not always of unfailing reliability. Prof. Ismail Araci of Stanford University (USA) and his colleagues have therefore developed a sensor that can measure intraocular pressure more precisely.
The great novelty of this sensor is that it can be implanted in the eye, thus allowing a continuous follow-up of the disease in people in the early stages of glaucoma. This sensor functions as a small barometer. The intraocular pressure causes a liquid to move the sensor. Movements can be recorded by a "smart" camera with a special optical adapter. To pose this sensor, the researchers suggest to implant it in a lens comparable to that which is implanted in the eye of the operated persons of the cataract.
But, at the moment, the work of Stanford researchers has been limited to animals. The sensor has not yet been tested in humans. Furthermore, it is impossible at the moment to know if the sensor is capable of functioning for several years. Further work is therefore needed before this sensor arrives on the market.
Research is moving ahead in ophthalmology, both in terms of surgery and drugs. Everything you need to know to benefit from it and keep a good view, good eye.
One Frenchman in two wears glasses or corrective lenses. Among them, many seniors. A good reason to be careful with his retina, the only structure of the eye still irreplaceable, and control his eyesight regularly. According to the Barometer 2008 of the National Association for the improvement of the site (As nav), 63% of the French have verified their site during the last twelve months; They were only 48% three years ago. But nearly four out of ten Frenchmen neglect this organ of the senses, probably because they do not know the risks involved. "Without treatment, they play with their eyes," warns Dr. Laurent Benzacken, head of the ophthalmology department at the Robert-Ballanger Hospital (Aulnay-sous-Bois). Here are the advances that you will benefit all the better when you have identified a visual impairment early.
• Slow aging of the retina
Like all tissues in the human body, the retina grows old. It possesses a purification system which allows it to get rid of the free radicals (all toxic waste) responsible for its premature aging. But this system tends to function less and less well over the years.
What is new: we know how to help the retina to better protect itself from free radicals produced by ultraviolet and pollutants.
In practice: two carotenoids (lutein and zeaxanthin) play the protective role. It is enough to consume certain fruits and vegetables (asparagus, cabbage, broccoli, zucchini, spinach, peas, peppers, oranges, corn, kiwi, grape ...) to refuel. Our carotenoid needs (6 mg / d) are covered by the daily intake of five fruits and vegetables, at least one of which contains the most.
Other measures to be taken immediately: stop smoking - which generates a maximum of free radicals - and exercise a physical activity - not less than 10 minutes a day - in order to soften the wall of the arteries and thus reduce the risk of Obstruction of the small fetal vessels of the retina. The sport also promotes the use of blood sugar by the cells and helps to limit the occurrence of diabetes (dangerous for blood vessels and the retina). Finally, you should sleep in the dark and protect yourself from the ultraviolet by wearing sunglasses.
Age-related macular degeneration (AMD) affects 30% of people after 75 years of age and 90% after 90 years of age at varying degrees of severity. It all begins with the impression of lack of light and a sensation of fog in front of the eyes. At this point, it is advisable to make an appointment with an ophthalmologist.
Macular degeneration can then follow two pathways. In the "dry" form, the most frequent but slowest evolving form, the retina progressively atrophies until loss of central vision. There is currently no treatment to cure it. Another, more severe form of "wet" is characterized by the formation of abnormal vessels in front of the retina. If they begin to bleed, it becomes impossible to see in front of them, to read, to drive or to watch television. Central vision is lost, only peripheral vision is preserved.
• Early in the dry form of the disease, dietary supplements (vitamin C and E, beta-carotene, zinc, and omega-3) reduce the occurrence of complications at five years by 25%. These supplements are not covered by Health Insurance.
In the wet form, progress has been made with the development of recent medicines, which are effective in stopping its evolution, but very expensive: Lucentis® (€ 1,200 per dose) and Macugen® (around € 700). A new treatment upsets the situation. Avastin ® initially intended for colon cancers, has the same effects as Lucentis® in intraocular injection, for a cost 40 times less (30 €)! This medicine has not yet received marketing authorization in this indication but is available for colon cancer, and hospitals are already using it. These three treatments address the growth factors (VEGF) that stimulate the abnormal vessel's thrust. They belong to the family of anti-VEGF, supported by the Health Insurance.
• In practice: these anti-VEGF class drugs are injected intraocularly, one injection every six weeks. Research is under way to propose, in the long run, a less restrictive oral form.
The challenge is large: to give vision to people with visual impairment or blindness due to a retina that has become out of service as a result of age-related macular degeneration (AMD), a frequent and often unrecognized condition. It is estimated that more than one million people have the disorder without knowing it.
What is new: the team of Professor José Sahel (head of the Rothschild Foundation in Paris and director of an Inserm unit) and Dr Serge Picaud (research director at Inserm) are currently working on The design of new-generation retinal prostheses made up of 256 sensors (compared to 16 until now) and a system capable of transforming the image into electrical signals. The first prostheses are being tested on the visually impaired. They will then, if their success is confirmed, more widely proposed. To obtain a result, it is imperative that the optic nerve is intact, which is no longer the case when glaucoma reaches an advanced stage. Hence the interest of detecting it at the earliest and of slowing as much as possible the evolution.
In practice: the devices currently tested are in the form of spectacles. The branches of these glasses are equipped with mini-cameras connected to a tiny computer, which stimulates the cells of the retina still functional so that they transmit their message to the brain. The ambition of these prostheses is to allow the implanted persons to read the large print and recognize the faces. A big step towards a new vision!
By Nathalie Shapiro - November 2008 November 20, 2008, modified August 26, 2014
Chronic glaucoma, a softer technique
The eyeball is an inextensible shell in which the aqueous humor is permanently secreted. This liquid is evacuated via a channel. In the event of an obstacle, it remains inside the eye and the pressure increases, compressing the fibers of the optic nerve. Now, what is wronged is irretrievable. Problem: chronic glaucoma (80% of cases) can evolve for years without the slightest symptom. When a veil appears before the eyes, part of the optic nerve is already lost.
• What is new: in some cases, medicines are sufficient. Otherwise, the ophthalmologist, who hitherto has no choice but to create a fistula in the tissue through which the fluid flows normally, resorts to laser or surgery under local anesthesia.
A promising technique has recently emerged: pneuma- trabeculoplasty (PNT). It consists of exerting a quasi-painless "sucking" around the eye with a device placed around the face to make this trabecular permeable without surgery.
The sequences are simple: the eye becomes a little red and the vision disturbed for a few hours. Violent efforts should be avoided and anti-inflammatory eye drops and antibiotics should be used for several weeks.
On the research side, new eye drops are expected to stabilize the pressure inside the eye. Better: eye drops to be used once a month is expected in the near future.
A promising technique has recently emerged: pneuma- trabeculoplasty (PNT). It consists of exerting a quasi-painless "sucking" around the eye with a device placed around the face to make this trabecular permeable without surgery.
The sequences are simple: the eye becomes a little red and the vision disturbed for a few hours. Violent efforts should be avoided and anti-inflammatory eye drops and antibiotics should be used for several weeks.
On the research side, new eye drops are expected to stabilize the pressure inside the eye. Better: eye drops to be used once a month is expected in the near future.
Finally, researchers are working on the development of drugs that can regenerate the optic nerve (the only way to reduce visual impairment), but it will probably take several years before commercialization.
• In practice: glaucoma affects 0.5% of 40-year-olds and 5% of those over 65 years of age. To avoid being part of the 400 000 glaucomatous who are unaware of their disease, it is necessary to have to check its eye pressure in the ophthalmologist imperatively every year. The salaries are paid by the Social Security.
With age (and sometimes ocular trauma), the lens becomes opacified, resulting in a loss of vision, with a foggy feeling in front of the eyes. The opaque part of the lens must then be replaced. The operation of cataract is one of the most frequent interventions in France: nearly 400 000 people are operated each year.
• What is new: the defective lens is destroyed with ultrasound or vibratory oscillations, then extracted by an incision and replaced by an implant, which can also improve vision. Recent advances concern the size of these implants, so small (by folding) that a minimal incision is enough to let them pass. However, the smaller the incision of the lens, the lower the risk (especially infectious) and the rapid healing.
In addition, implanted implants can correct other vision defects, such as myopia: enough to kill two birds with one stone!
• Medical appointments: shortened deadlines
Sometimes it takes months - especially in the North, Center, and East - to get an appointment with the ophthalmologist. The lack of doctors trained in this specialty for years is for many.
• What is new: the law allows opticians to renew glasses or corrective glasses directly, on the express condition that the prescription (established by an ophthalmologist) is later than April 15, 2007 (date of publication of the decree) and that The optician discovers no new anomaly of the vision. This measure mainly concerns people under the age of 50 who, for the most part, have less need for close supervision. Seniors, on the other hand, can not escape from a visit to the specialist, especially in the case of diabetes or glaucoma.
• In practice: if younger people follow this instruction, the difficulties of obtaining a medical appointment within a more reasonable period of time should decrease slightly, but not be reduced because the number of ophthalmologists practicing in our country remains insufficient. The good resolution is to go ahead well in advance!
• When to visit my ophthalmic to Glaucoma?
- In an emergency: in the case of the red or painful eye, one does not lose a minute to consult. It is clear to the secretary that it is an emergency in order to be received without delay. The same thing happens in the case of luminous flashes, because, with the exception of migraineurs, in whom they can announce a crisis, these symptoms mostly give rise to fear of tearing the retina. Attention, finally, with the decline of the sight, even transitory, which can testify a clot in a small artery!
- According to his age and other pathologies: from 45 years, the age of presbyopia, one must see his ophthalmologist every 12 to 18 months. And even every six months in the case of high blood pressure or diabetes because the attack of the arteries nourishing the retina is then frequent. Being a smoker, having an excess of bad cholesterol, being overweight and sedentary are other vascular risk factors.
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